Establishment of local diagnostic reference levels for commonly performed computed tomography examinations in Thai cancer hospitals

Abstract

Background: The International Commission on Radiological Protection (ICRP) introduced the use of Diagnostic Reference Levels (DRLs) for imaging procedures. DRLs are dose levels used as a reference for reducing radiation exposure to patients. In Thailand, DRLs for Computed Tomography (CT) examinations of cancer hospital is not established at this moment. Objective: This work aimed to survey and establish DRLs for common CT examinations in Thai cancer hospitals. Methods: Eight Thai cancer hospitals were surveyed for Volume Computed Tomography Dose Index (CTDI_vol)and Dose Length Product (DLP). Each has its imaging facility with a CT scanner. Each facility was asked to fill out a questionnaire regarding 1 year of CT examinations for 4 body parts including the brain, head and neck, chest, and abdomen. Values of DRLs were established by using the 75^thpercentile of CTDI_vol and DLP. Results: 2,464 CTs comprise 576, 588, 656, and 644 examinations for the brain, head and neck, chest, and abdomen, respectively. The 75^th percentile or DRLs of CTDI_vol (mGy) and DLP (mGy.cm) of brain CT were 77.30 and 1198.80, respectively. For head and neck CT were 19.20 and 541.90, respectively. For chest CT were 24.30 and 771.84, respectively and for abdomen CT were 21.00 and 845.65, respectively. Conclusions: The values of DRLs obtained from this study were higher than those reported from European countries. Strategies for CT dose optimization for each hospital should be applied to minimize patient’s radiation exposure.